Drive for electric clocks



Nov. 25, 1969 KRUGER 3,479,814

DRI VE FOR ELECTRIC CLOCKS Filed March 10, 19s? INVENTQR. GUSTAV KRUGER ATTORNEYS United States Patent" Int. Cl. Gim 1/06 US. CI. 58-41 Claims ABSTRACT OF THE DISCLOSURE An electric clock having a first movable means which is driven by a spring and which moves in a given direction during tensioning of the spring, the clock having a second movable means to which the drive is transmitted from the first movable means by a transmission means which coacts with the first and second movable means. This transmission means assumes during movement of the first movable means in the above direction while the drive spring therefor is tensioned a position completely spaced from at least one of movable means so that the transmission between the first and second movable means is completely interrupted Without any frictional or mechanical engagement of any type between components of the transmission while the spring which drives the first movable means is tensioned.

BACKGROUND OF THE INVENTION The present invention relates to transmissions for transmitting a drive, and is particularly adapted for use in electric clocks.

Electric clocks are known wherein the drive for the clock is derived from a drive spring which is tensioned from time to time by a motor or by a swingable armature of an electromagnet, for example. When this spring has been tensioned, it is necessary to transmit the drive therefrom to the components of the clock by way of a transmission which will not permit the tension of the drive spring to become immediately dissipated once the drive spring is tensioned but which will rather provide a steady running of the clock components while the drive spring runs down.

Conventional transmissions of this type include a ratchet wheel having teeth of sawtooth configuration coacting with a pawl. During tensioning of the drive spring the pawl rides over the teeth of the ratchet wheel, providing in this way an extremely disturbing noise. When the tensioning of the drive spring has been completed, the pawl snaps into the gap between a pair of teeth of the ratchet wheel and thus takes over the transmission of the drive to the components of the clock.

Constructions of this type operate satisfactorily and can be manufactured at favorable costs. However, they have the disadvantage of creating undesirable noise during tensioning of the drive spring, so that structures of this type cannot be used in rooms or for alarms unless there is combined with the clock an expensive structure for eliminating the noise which results during tensioning of the drive spring.

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a transmission of the above type which is also reliable in operation and inexpensive to manufacture but which will in addition operate in a practically sound-free manner, particularly during tensioning of the drive spring, so that the clock of the present invention can be used in rooms and for alarms without requiring any special measures to be taken to suppress noise resulting from tensioning of the drive spring.

Patented Nov. 25, 1969 It is also an object of the invention to provide a clock which will operate with less friction losses than conventional clocks, while at the same time conserving energy so that in the case of a battery-driven clock, for example, the life of the battery is lengthened, as compared to conventional clocks driven by the same batteries, these results being achieved concomitantly with the sound-free operation.

Furthermore, it is an object of the present invention to provide a clock whose components will have a reduced mechanical wear, as compared to conventional constructions using a pawl and ratchet, for example.

With the construction of the invention, a first movable means which is driven by the drive spring of the clock moves in a given direction during tensioning of the drive spring. A second movable means of the clock is to be driven from the first movable means, and for this purpose the invention provides a transmission means which coacts with the first and second movable means for transmitting the drive from the first to the second movable means exclusively by friction, this transmission means automatically assuming, during movement of the first movable means in the above direction while the drive spring is tensioned, a position completely spaced from at least one of the movable means so that there is a complete interruption, without any mechanical or frictional engagement of any type, in the transmission from the first to the second movable means, thus providing the above-discussed features of sound-free operation, reduction in friction, and reduction in mechanical wear of the components. During the transmission of the drive from the first to the second movable means, a friction surface of the transmission means presses against the second movable means to transmit the drive thereto without slippage exclusively by way of friction forces, the transmission means including a lever which is turnably carried by the first movable means for movement therewith and which carries a friction memher which has this friction surface which is pressed in the manner of a wedge against a surface of the second movable means during transmission of the drive thereto. The friction member of the transmission means can take the form of a wedge or it may take the form of an eccentric member.

The dimensions of the friction member, whether it be in the form of an accentric or a Wedge, are determined by the operative coefiicient of friction between the friction surface and the second movable means which takes the form of a rotary member having a circular periphery frictionally engaged by the friction surface of the friction member of the transmission means. These dimensions will be determined by the magnitude of a force N which acts normally against the circular periphery of the rotary member which forms the second movable means, this force being determined by the relationship where the necessary friction force R is achieved through this relationship, with p. being the coefficient of friction between the friction member and the peripheral surface of the rotary member against which it presses.

BRIEF DESCRIPTION 'OF THE DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a fragmentary schematic illustration of one possible embodiment of a structure according to the invention showing the parts in the position they take during transmission of the drive;

FIG. 2 shows the parts of FIG. 1 in the position they take during tensioning of the drive spring;

FIG. 3 is a schematic illustration of another embodiment of a structure of the present invention shown in FIG. 3 during transmission of the drive;

FIG. 4 is a schematic illustration of yet another embodiment of a structure according to the present invention, FIG. 4 also showing the parts in the position they take during transmission of the drive; and

FIG. schematically illustrates parts used with the structure of FIGS. 1 and 2.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, there is shown therein a rotary drive wheel 1 which forms the second movable means of the structure of the invention. This rotary drive wheel 1 is in the form of a circular member which rotates about its axis and which has an outer circular periphery of a suitable coefiicient of friction for a purpose described below. This rotary drive member 1 is operatively connected with an unillustrated gear transmission of the clock for transmitting to the latter gear transmission of the clock the force of the driving spring. While it is driven, this second movable means 1 rotates in a clockwise direction, as indicated by the arrow a in FIG. 1. This rotary member 1 assumes the location occupied by the ratchet Wheel in the conventional constructions referred to above. Thus, the member 1 has no teeth but it can be provided at its outer periphery with a surface which is roughened within certain limits. This member 1 can be made of metal or it can, with advantage, be made of plastic which has a high coefiicient of friction. For example, this plastic may be that which is known under the trade name Vulkollan, which is known to have a Shore Hardness of 90.

A lever 2 is operatively connected with the drive spring of the clock to be driven thereby, and this lever 2 forms the first movable means of the structure of the invention. When this first movable means 2 is driven by the drive spring of the clock it moves in the direction of the arrow b shown in FIG. 1. During tensioning of the drive spring, however, the lever 2 moves in a given direction which is opposite that indicated by the arrow b.

With the embodiment of FIGS. 1 and 2, the trans mission means which coacts with the pair of movable means 1 and 2 includes a lever 3 which is pivotally carried at 9 by the movable means 2. A spring 7 is connected at one end to the movable means 2 and at its opposite end to the lever 3 to urge the latter to turn in a clockwise direction, as viewed in FIGS. 1 and 2, this spring 7 also forming part of the transmission means. The lever 3 carries a friction member at its left end, as viewed in FIGS. 1 and 2, and this friction member terminates in a friction surface 8 which frictionally engages the outer periphery of the rotary member 1, in the position of the parts shown in FIG. 1. The lever 3 carries an electrical contact 4, and in addition the lever 3 carries a motiontransmitting pin 5 which is adapted to coact with a projection 6 which is integral with an extension from the movable means 2, as indicated in FIGS. 1 and 2. The friction member at the left end of the lever 3 is integral with the latter in the illustrated example, and the friction surface 8 thereof eXtends along an eccentric curve. For example, this convexly curved friction surface 8 forms part of a circle whose center is situated to the right of and somewhat lower than the point 9 where the lever 3 is connected to the movable means 2, as viewed in the drawings, so that as the lever 3 turns in a clockwise direction about the pivot point 9, as viewed in the drawings, the surface 8 is pressed against the periphery of the movable means 1, while when the lever 3 is turned in a counterclockwise direction, as viewed in the drawings, in opposition to the force of the spring 7, the friction surface 8 will be displaced away from the outer periphery of the movable means 1. The contact 4 serves not only as the contact of an electrical circuit but also as a motion-transmitting member.

With this construction, when the parts have the position of FIG. 1, the surface 8 is pressed in a wedging, clamping manner against the periphery of the rotary drive wheel 1, so that the latter is driven without slippage in the direction of the arrow a. The eccentricity of the curved friction surface 8 with respect to the rotary point 9 of the lever 3 is so chosen, depending upon the coefiicient of friction which is effective between the parts 1 and 8, that the frictional engagement between these parts will take place without slippage.

FIG. 2 illustrates the position which the parts take during tensioning of the unillustrated drive spring which drives the lever 2. The contact 4 coacts with a contact carried by the movable armature of an electromagnet which is situated in a known electrical circuit. When the spring which drives the movable means 2 has run down to a given extent so that the movable means 2 has been displaced thereby to a predetermined location, the contact 4 engages the armature contact which is situated in the path of movement of the contact 4 so as to close the circuit and energize the electromagnet thus displacing the armature in the direction of the arrow C shown in FIG. 2, and in this way the armature pushes the contact which it carries against the contact 4 so as to swing the lever 3 in opposition to the spring 7 from the position of FIG. 1 into the position of FIG. 2 while simultaneously returning the lever 2 into its initial position and tensioning the drive spring. It will be noted that at this time the motion-transmitting pin 5 which is carried by the lever 3 engages the projection 6 of the movable means 2 so as to limit the turning of the lever 3 from the position of FIG. 1 into the position of FIG. 2, as well as to limit the extent to which the spring 7 is tensioned, and in this way the transmission means of FIGS. 1 and 2 serves not only to transmit the drive from the movable means 2 to the movable means 1, when the parts have the position shown in FIG. 1, but also to transmit the tensioning movement from the armature of the electromagnet through the lever 3 of the transmission means to the movable means 2 so as to retract the latter to its initial position while tensioning the drive spring.

Simultaneously with these tensioning operations the friction surface 8 of the friction member carried by the lever 3 is displaced away from the outer periphery of the rotary movable means 1, so as to be entirely spaced therefrom, as is apparent from FIG. 2. As a result, during tensioning of the spring which drives the movable means 2 there is absolutely no mechanical contact, frictional or otherwise, between the transmission means and the movable means 1. When the armature of the electromagnet has reached the end of its driving stroke, the electrical circuit of the electromagnet is interrupted in a known way, the armature is immediately retracted to its starting position, and the spring 7 now acts automatically to return the friction surface 8 into engagement with the outer periphery of the movable means 1, so that the driving operations continue. This transmission of the drive will continue until the contact 4 again engages the contact carried by the armature of the electromagnet, and then the above operations will be repeated.

FIG. 5 schematically illustrates the drive spring 20 operatively connected with the movable means 2 which is swingable about the axis of the movable means 1. The movable means 2 together with the spring 20 form part of an electrical circuit which includes the battery 16, the electromagnet 17, and the armature 18 which automatically assumes the rest position shown in FIG. 5 when the electromagnet 17 is unenergized. The armature 18 carries at its right free end, as viewed in FIG. 5, a contact 19 which is adapted to coact with the contact 4. The circuit is completed through the armature 18, the contacts 19 and 4, the lever 3, the pin 9, and the movable means 2, so that in this way when the contact 19 is engaged by the contact 4, the solenoid will be energized. The parts are shown in FIG. 5 just at the instant when the contact 4 has engaged the contact 19. Thus, the electromagnet 17 will be energized to swing the armature 18 upwardly around a pivot connected to its left end, as viewed in FIG. 5, and in this way the movable means 2 will be retracted back to its initial position, thus tensioning the spring 20. During the turning of the armature 18 its contact 19 slides to the right with respect to the contact 4, while the latter slides to the left with respect to the contact 19, as viewed in FIG. 5, so that after a given increment of angular return movement of the movable means 2, the contacts 19 and 14 will move out of engagement with each other to open the circuit, the armature 18 returning to its rest position shown in FIG. 5 and the spring 7 acting to return the lever 3 to its operating position as described above.

With the embodiment of the invention which is illustrated in FIG. 3, instead of providing on the lever of the transmission means which is turnably carried by the movable means 2 an integral friction member having an eccentric friction surface, the movable means 2 carries, for turning movement, a lever of the transmission means, and this lever 10 in turn pivotally carries, at a friction member 14 in the form of a wedge. In this case the wedge member 14 frictionally engages not only the outer periphery of the movable means 1 but also the outer periphery of the lever 2 at the convexly curved outer peripheral edge of the free end portion of the movable means 2 which is illustrated in FIG. 3. The angle of the wedge 14, which forms the friction member of this embodiment and which has the inclined friction surfaces engaging both movable means, is chosen, depending upon the coeflicients of friction between the various materials which frictionally engage each other, so that self-locking occurs and friction transmission takes place without slippage. Thus, in this case also the transmission means formed by the lever 10, the spring 7, the friction member 14 and its friction surfaces, will transmit the drive in a frictional manner without slippage. The spring 7 is connected in this embodiment at one end to the movable means 2 and at its opposite end to the lever 10, so as to urge the latter to turn in a clockwise direction, as viewed in FIG. 3. Thus, the spring 7 acts to push the oppositely inclined friction surfaces of the wedge 14 against the coacting friction surfaces of the pair of movable means 1 and 2.

With this embodiment also the lever 10 carries the contact 4 in whose path of movement the contact carried by the armature of the electromagnet is situated, so that when the drive spring runs down to a give extent so as to situate the movable means 2 at a given location, the contact 4 will have been displaced into engagement with the contact carried by the armature of the electromagnet, closing the circuit of the latter and causing the lever 10 to swing in opposition to the spring 7 in a counter-clockwise direction. In this embodiment the turning of the lever 10 at this time is limited by engagement of the lever 10 with the pin 5 which is directly carried by the movable means 2, so that in this case also the transmission means coacts with the movable means 2 during tensioning of the drive spring to retract the movable means 2 back to its initial position while the drive spring is tensioned by the movement of the armature which acts on the lever 10 at the contact 4 carried thereby. At the end of the driving stroke of the armature the circuit opens, the armature is retracted, and the parts again assume the position shown in FIG. 3 so that the driving of the movable means 1 now continues and the above operations will again be repeated when the spring runs down to a given extent. With this embodiment also it is apparent that when the lever 10 is turned in opposition to the spring 7 into engagement with the pin 5, the friction member 14 will be spaced from the outer periphery of the movable means 1 so that there will be absolutely no mechanical contact of any type with the latter during the tensioning of the drive spring.

In the embodiment of the invention which is illustrated in FIG. 4, the contact 4 is not carried by a lever which is turnably connected with the movable means 2. Instead the contact 4 is directly carried by an extension of the movable means 2, as illustrated in FIG. 4. In this case the wedge 14 which operates in the same way as the wedge 14 of FIG. 3 is pivotally carried by a lever 11 which is pivotally mounted on the movable means 2 and which is acted upon by the spring 7 so as to be urged to turn in a clockwise direction placing the oppositely inclined friction surfaces of the friction member 14 in frictional engagement with the pair of movable means 1 and 2, respectively. Thus, this embodiment also is capable of achieving a friction transmission without any slippage during transmission of the drive from the movable means 2 to the movable means 1.

When the drive spring has run down to a predetermined extent so as to locate the lever 2 in a predetermined position, the contact 4 which is directly carried by the lever 2 in this embodiment will engage the contact carried by the armature of the electromagnet so that the latter will become energized and in this case the thrust derived from the armature upon energizing of the electromagnet will cause the armature to move in the direction of the arrow d throwing the lever 2 forcefully in a direction opposite to that in which it moves during transmission of the drive to the movable means 1, so that the movable means 2 is forcefully and suddenly retracted back to its initial position while the driving spring is tensioned.

With this embodiment the inertia of the lever 11 and the friction member 14, together with the force of the spring 7, are carefully chosen so that in response to the inertia forces the lever 11 and the wedge member 14 do not follow the retraction movement of the movable means 2, but instead the spring 7 is tensioned as a result of this inertia while the friction member 14 is displaced away from the outer periphery of the movable means 1, and thus in this case also there is no mechanical engagement of any type between the movable means 1 and the transmission means during tensioning of the drive spring. Thus, with the embodiment of FIG. 4 as well as with the abovedescribed embodiments, during tensioning of the drive spring the transmission means is spaced from the movable means 1 so as to have absolutely no engagement therewith of any type. Thus, with the embodiment of FIG. 4 the movable means 2 will be retracted without any frictional resistance with respect to the movable means 1 back to the starting position where the drive spring has its maximum tension. At the end of the driving stroke of the armature the circuit is again opened, and as soon as the movable means 2 terminates its retraction movement, the spring 7 automatically returns the wedge 14 into its posltion clamped between and frictionally engaging the pair of movable means 1 and 2, so that the drive again resumes. Thus, with all of the embodiments of the invention it is possible to achieve with a relatively inexpensive structure which is simple and easy to manufacture a soundless tensioning of the drive spring with the additional advantages of no frictional engagement between the transmission and the movable means 1 during tensioning of the drive spring so that the energy is conserved and the life of a battery, for example, is prolonged and the reduction in the wear of the parts resulting from the spacing therebetween during tensioning of the drive spring.

What is claimed is:

1. In an electric clock, first movable means for transmrtting a drive from a tensioned spring, said first movable means moving in a given direction during tensioning of the spring, second movable means for driving components of the clock, transmission means coacting with said first and second movable means for transmitting the drive from said first to said second movable means, and electrical means coacting with said first movable means for moving the latter in said given direction to tension the spring while placing said transmission means in a condition assuming a position spaced from at least one of said movable means during movement of said first movable means in said direction while said spring is tensioned, so that there is a complete interruption, without any frictional or mechanical contact of any type, in the transmission from said first to said second movable means during tensioning of the spring which drives said first movable means.

2. The combination of claim 1 and wherein said transmission means coacts with said first and second movable means for providing an exclusively frictional transmission of the drive from said first to said second movable means.

3. The combination of claim 2 and wherein said transmission means is carried by said first movable means for movement therewith and frictional engages said second movable means for transmitting the drive thereto.

4. The combination of claim 3 and wherein said second movable means includes a rotary member having an outer circular periphery and said transmission means having a friction surface pressing against said periphery of said rotary member during transmission of the drive from said first to said second movable means.

5. The combination of claim 4 and wherein said transmission means includes a lever turnably connected to said first movable means and having a position during tensioning of the spring while said first movable means moves in said direction different from its position when said friction surface engages said periphery of said rotary member, and said lever, when in said position thereof during tensioning of the spring which drives said first movable means, coacting with said friction surface for displacing the latter to a location spaced from said periphery of said rotary member.

6. The combination of claim 5 and wherein said transmission means responds to inertia forces for locating said lever in said position where said friction surface is spaced from said periphery of said rotary member during tensioning of the spring which drives said first movable means.

7. The combination of claim 5 and wherein said transmission means coacts with said first movable means for displacing the latter in said direction during tensioning of the spring which drives said first movable means, and said transmission means, when acting on said first movable means to displace the latter in said direction, locating said lever in said position where said friction surface is spaced from said circular periphery of said rotary member.

8. The combination of claim 4 and wherein said rotary member is composed at least at the region of its outer periphery of a plastic having a coefficient of friction which provides a substantially slip-free transmission of motion from said friction surface to said rotary member.

9. The combination of claim 4 and wherein said friction surface forms part of a plastic member having a coefficient of friction which will provide substantially slipfree transmission of motion from said friction surface to said rotary member.

10. The combination of claim 1 and wherein said transmission means includes a lever turnably carried by said first movable means and carrying a friction member which has a friction surface engaging said second movable means to transmit the drive frictionally thereto, and a spring connected to said lever and to said first movable means for placing said lever in a position where said friction surface thereof presses against said second movable means.

References Cited UNITED STATES PATENTS 1,801,985 4/ 1931 Schcenker. 3,163,727 12/1964 Eshleman 58--4l 3,261,935 7/1966 Rogers 58-41 RICHARD B. WILKINSON, Primary Examiner EDITH C. SIMMONS, Assistant Examiner U.S. Cl. X.R. 318-127 

